The present invention relates to cleaners for machine dishwashing, in particular those cleaners that provide the advantages of a cleaner and a rinse aid in one product, and to production methods for such cleaners.
German patent application DE 100 32 612.9 discloses the use of copolymers of i) unsaturated carboxylic acids, ii) monomers containing sulfonic acid groups, and iii) optionally further ionic or nonionic monomers in machine dishwashing agents. Rinse aids and machine dishwashing agents that comprise such polymers are likewise described, which agents can be prepared in solid or liquid form, e.g. as powders, granules, extrudates, tablets, liquids, or gels.
Usually, polymers for the detergents and cleaners industry are sold in the form of aqueous solutions of concentrations between 30 and 60% by weight. These solutions can be used directly in the customary processing steps, for example granulation. The copolymers containing sulfonic acid groups described in DE 100 32 612.9 are processed in this way with great difficulty, since the corresponding solutions are considerably tacky and impair the formation of homogeneous, flowable mixtures. In addition, particulate products into which the polymer has been incorporated from its delivery form have a tendency to clump, thus lowering consumer acceptance, while tableted products have problems such as after-curing and poor dissolution properties.
These problems are further exacerbated in product forms that have been consumer- and wash-program-optimized by combining a number of conventional products. In order, for example, to provide cleaning products with rinse aid performance, large amounts of nonionic surfactants are needed. Such substances with low melting and softening points can likewise only be incorporated with extreme difficulty and make the additional incorporation of the copolymer in typical solution form virtually impossible. Incorporating relatively large amounts of copolymers containing sulfonic acid groups in the presence of relatively large amounts of readily melting compounds is therefore a problem that severely restricts the freedom to formulate.
It therefore was an object of the present invention to provide a solid machine dishwashing agent that comprises copolymers containing sulfonic acid groups in any amount, without giving rise to product problems such as clumping, after-curing, or poor dissolution properties. In addition, the aim was to provide a method that permits incorporating copolymers containing sulfonic acid groups into machine dishwashing agents in any desired amount, without the process safety being impaired or the production apparatuses becoming permanently contaminated.
It has now been found that the described problems can be solved if the copolymers containing sulfonic acid groups are added to the cleaners in particulate form. Surprisingly, the incorporation of the polymers within a certain particle size distribution is particularly advantageous. In this way, high amounts of polymer can also be incorporated into the cleaner in the presence of large amounts of readily meltable or softenable substances.